In an ideal Brayton cycle, air is compressed from 84 kPa and 25°C to 840 kPa. Under cold air standard conditions, the thermal efficiency of this cycle is
A)48%
B)52%
C)10%
D)60%
E)74%

Question

Quizplus · Accepted Answer

Solved by EES Software. Solutions can be verified by copying-and-pasting the following lines on a blank EES screen. 
P1=84 "kPa"
P2=840 "kPa"
T1=25+273 "K"
rp=P2/P1
k=1.4
Eta_Brayton=1-1/rp^((k-1)/k)
"Some Wrong Solutions with Common Mistakes:"
W1_Eta = 1/rp "Taking efficiency to be 1/rp"
W2_Eta = 1/rp^((k-1)/k) "Using incorrect relation"
W3_Eta = 1-1/rp^((k1-1)/k1); k1=1.667 "Using wrong k value"

In an Ideal Brayton Cycle, Air Is Compressed from 84